We analyzed the causes of this anomalous presence of p27 in a group of aggressive B-cell lymphomas, including 54 cases of diffuse large B-cell lymphomas and 20 Burkitt's lymphomas.
High grade lymphomas showed markedly decreased p21 expression (3.9 in Hg-NHL vs. 12 in Lg-NHL and 29 in CLL; values expressed as mRNA transcripts x 10(3), p < 0.009). mRNA and protein expression of p27 was considerably higher in CLL than in the lymphomas.
We evaluated Cdc25A mRNA expression by in situ hybridization and p27 protein expression by immunohistochemistry in 42 histologically indolent B-cell non-Hodgkin lymphoma (NHL and 51 histologically aggressive B-cell NHL.
Moreover, we found that overexpression of miR-455-3p significantly elevated the protein levels of p27 kinase inhibition protein (KIP) 1, Bax, pro-caspase-3, and active caspase-3, and markedly downregulated the levels of B-cell lymphoma-2 (Bcl-2).
At the gene level, CADM1 expression level upregulated caspase-3 activity and expression of Bax and p27 protein and downregulated levels of B cell lymphoma-2, cyclinD1, cyclinE1 and cyclin dependent kinase 2 proteins.